Sleeping Pad R Values

Measuring Insulation

If you’re a home owner, you are probably familiar with the concept of an R-Value. If not, it’s a measure used in the building and construction industry to rate the thermal resistance of building insulation under specific test conditions. The higher the R value, the more effective it is.

R value performance testing is done in a 70 F environment with no air movement. As such, it doesn’t reflect many real world conditions where you’d use a sleeping pad, so I highly recommend that you augment any gear selection that you make based on it with field testing.

If you are interested in sleeping pads for early spring, late autumn or winter conditions, R-Value is additive. When it gets cold, I like to use two pads, a closed cell foam pad and an insulated inflatable one with a combined R-Value of at least 5.

For purposes of backpacking, you also need to factor in weight, comfort, compressibility, and rigidity when you make a sleeping pad selection. In addition, side sleepers may not receive the full R-value of benefit of an inflatable insulated pad because their bodies are not in full contact with the surface of the pad. This is particularly true for insulated sleeping pads that depend on your body heat to warm them up, including the Therm-a-Rest NeoAir product line, Exped’s DownMats and Big Agnes’ Insulated Pads.

Sleeping Pad R-Value Comparison

The following table provides a side by side comparison of the major sleeping pads available in the US market. The pad weights listed are sized for 72″ long x 20″ wide pads, though there are a few exceptions below. The R-Value of a pad should still remain the same if you select a longer, shorter, or wider variation of the pad. If a sleeping pad has a R-Value of “Not Available”, it’s because the manufacturer has not supplied one or R-value testing has not been performed.

Since my last comment I have done lots of research regarding r values and my daughter created a science experiment which received first place.

We emailed several big name companies to find out more of how they test r values. Most did not respond. Most couldn’t explain how they got their numbers but, Nemo equipment provided us with the hard facts. They used a few different methods to find temperature resistance. Some with hot plate and others with cold. No where do they test in real setting or as extensively as let’s say siding on a garage door, with the wind and other elemental factors. No one ever test with a real person.

They are trying to have a set standardized test. This is called the EN testing. Still, No natural elements and no human testing to my understanding. I personally don’t think that human testing can be accurate because we vary so much from person to person. There would be more factors to consider. Like are you properly hydrated? Your body temperature before the experiment and have you eaten recently, because we all know this can increase your body’s core temperature.

In the end my daughter (Alice Alldridge of 5th grade) used a medical water bottle(filled with water), inside a thinly insulated stuffed animal (a koala) starting temperature at 99°. She put the koala on a frozen roasting pan of ice and timed how long it took the koala to suffer from hypothermia of 82°. She tested a Mylar emergency blanket, refletix (reflective bubble wrap) and closed cell foam hiking mat. This may not be high tech but I think it’s a start. In the least to simulate a person being made up of mostly water.

Thanks for reading my update. I would love to hear your thoughts and read your opinions.

Congratulations on your daughter’s project! Sounds like she learned a lot about R value.

It’ll be a great day when the pad manufacturers let go of their “R-value” claims, and create a consistent comparison method. When the dust settles, people will realize that the air mattress values are totally over-inflated (pun intended). But to prove this, one must create a test where a side keeper is simulated, since there is more weight concentrated in the center of the pad. They also must simulate nighttime body movement, since the R-value of air mattresses is severely impacted by internal convection from any slight movement. Finally, the building indrusty has found that R-value changes with temperature. Given most of us would like to be comfortable at a cold air/ground temperature, this must be contemplated as well, for any of these values to offer any reliability in the real world. My understanding is many testing chambers are calibrated at temperatures above freezing. In our world where sleeping below freezing can be a life/death affair, sub-zero R value simulation must be considered.

Ha! The intro picture is a concrete, high efficiency house built by Walter Jefferies of Sugar Mountain Farms. One of my favorite blogs. I have learned a ton about the corruption in our food supply chain from this man.

CCF (closed celled foam) Pads will always offer you the highest (most consistent) R values compared with any mattresses which depend on inflated air to achieve their “warmth”.

While the X-Therm pad offers a high R value claim, and some folks believe it works well for them in the winter, there are just as many other folks that find it didn’t work well for them in the winter, giving rise to the inconsistency in the R value claims. Speaking from experience, I would NEVER go winter camping without a CCF pad to supplement my air mattress.

This is especially true if you sleep on your side, since air mattresses R value claims don’t consider side sleeping or any movement on the pad.

With all due respect, (with the exception of CCF or rigid insulation) the R value most certainly will change, since the thickness between my body and the ground has changed. (Roger Caffin’s BPL analysis clearly illustrated this back in 2011.)

The analogy that these pads are being heated up by our body, which in turn is what keeps us warm would be generally referred to as the “thermal mass” of a material. Thermal mass is not the same as an R value measurement, since R value is strictly about a material’s resistance to heat flow (technically the inverse thereof).

The bottom line: unless a pad manufacturer CLEARLY INDICATES that their air mattresses stated R value is an average based on a range of testing different thicknesses distortions, then there is no way to accurately determine what happens when one sleeps on their side vs. on their back.

Take the NeoAir’ older version of the All Season pad: It’s claimed R value is 4.9. in BPL’s testing, it had a measured range of R 6.1 all the way down to R 1.6. If I typically sleep on my side, I should be VERY CONCERNED about the bottom end of this range, since it might be more indicative of what I might actually experience.

Furthermore, for thick air mattresses, it is crucial to consider the it’s sides, since it is completely exposed to ambient air temperature (which is usually a LOT colder than the ground temp.) Any movement on the pad, and the air will circulate, thus reducing the R value.

Being in the architecture/building profession, I also wish to offer that emerging studies in the building science profession over the past few years have shown that R value of building products actually change when ambient temperature changes. As excerpted from a Building Science Corporation analysis:

“Again, all of the polyisocyanurate samples exhibit a significant decrease in thermal performance when the outdoor temperature is colder.”

I don’t mean to sound like an alarmist, but I worked in the outdoor retail world for many years (while studying to be an architect), and I watched how pad manufacturers began using R value claims for their marketing purposes (in the mid 90’s thru early 2000’s). Since that same time in the building profession, a lot has changed in the both the understanding and implementation of R-value for various building products.

While I understand various companies have been discussing it for a while, I have not seen any tangible efforts of “R value standardization” in the outdoor equipment industry. Because of the variables, I would be highly skeptical of any R value claims, especially in relation to mattresses which heavily depend on inflated air for their R value – even different models by the same company.

Absolutely, but I the absence of any other metric, it’s what we have. I have been in touch with the people working on more common standard For measuring sleeping pad insulation but it’s slow going as you can imagine.

I believe – if the pad is compressed more the R value would go down – the insulation value (R value) is due to the small air pockets between you and the cold place – if compressed the pad will be lwss efficient.